Why was the Marina District, San Francisco, heavily damaged in the 1906 and 1989 quakes?
A. Shaking was no more extensive than elsewhere in the city, but the whole district burned following each quake.
B. The epicenters of both quakes were right under the district.
C. Liquefaction and foundation failures were common.
D. The area is built on consolidated rock, causing the shaking to be amplified.